Whereas most animals shed and regrow hair seasonally, humans shed about 100 strands of hair out of about 100,000 strands and about 100 strands regrow every day, thus always maintaining a similar number.
The hair growth cycle consists of anagen, catagen and telogen phases. During the anagen phase, hair growth is promoted as cell division occurs actively in the hair dermal papilla and hair grows only in this stage. Considering that the anagen is about 3-5 years for men and about 4-6 years for women, about 80-85% of hair is in the anagen phase. In the catagen phase, which lasts about 3-4 weeks, the cell division declines gradually. Lastly, in the telogen phase, the hair dermal papilla is withdrawn and the hair separated from the capillary vessel and simply stuck in the scalp. This lasts about 3 months and the hair in the telogen phase is easily lost upon physical stimulation.
Although hair is not an organ critical in sustaining life, it is an indicator of health state and an important part of the body in terms of appearance. Whereas hair loss is considered a normal physiological event for those with a lot of hair, those who suffer from severe hair loss can be badly affected in terms of mental well-being and quality of life due to depression, sense of shame, social isolation, etc.
Although promotion of hair growth and prevention of hair loss have been studied from ancient times, the mechanisms of hair growth and hair loss have not been elucidated clearly yet. Recently, cytological, biochemical or molecular biological studies are actively carried out globally on hair growth and hair loss in many research institutes of universities and companies. Also, a lot of efforts are being made on the development of a drug that can treat hair loss and promote hair growth.
(Patent document 1) KR10-2010-0116882 A.